| The roe processing wastewater has the quality characteristics of high concentration of chemical oxgen demand,high concentration of nitrogen and phosphorus and high salinity,which are different from the general aquatic products processing wastwater.The roe processing wastewater is easy to produce large amount of foam in the biochemical pool when disposed by biochemical treatment directly and the phenomenon of ammonia nitrogen higher than influent is easier to occur.Not only the difficulty of domestication of microorganisms is increased but also the effect of biochemical treatment is reduced because of the high salinity of the wasteaer.The water quality is difficult to meet the standard when treated by biochemical treatment directly in the actual production.To solve the above problem,the pretreatment of roe processing wastewater should be strengthen.In order to solve the problem when the water treated by biochemical directly and make the wastewater meet the discharge standards,this paper studied the effect of coagulation treatment on roe processing wastewater.This paper adopted the polyaluminium chloride,aluminium sulphate,ferric chloride and polymeric ferric sulfate of four kinds of coagulants to pretreat roe processing wastewater produced by a aquatic produces processing factory in Qingdao.This paper studied the optimal pH value and dosage of each coagulant,and analyzed the removal efficency of COD,total phosphorus and inorganic phosphorus by coagulation and selected the best coagulant by comparison of coagulation efffect.This paper studied the relationship between primary and secondary of the various affecting factors with the best coagulant and the optimal conditions of coagulation.The results showed that,the best coagulant was ferric chloride with the optimal pH value of 7,the best dosage of 660 mg/L.The removal rates of COD,total phosphorus and inorganic phosphorus were 59.3%,97.7% and 97.5% respectively.Compared with the other coagulants used in the paper,the ferric chloride has the advantages of better treatment effect and lower cost.The iron residued in the wastewater can maintain normal activities of the microorganism in the biochemical pool,and the aluminum salt coagulant can not achieve this.According to the results of orthogonal test,the primary and secondary factors affecting coagulation treatment of roe processing wastewatwer were as follows: stirring method,dosage of ferric chloride,pH value and settling time.The opti mal conditions of the coagulation were dosage of ferric chloride with 660mg/L,the pH value of 7,the stirring method of 120r/min for 1 min and 80r/min for 15 min,and settling time for 30 min.The removal rate of COD and phosphorus in roe processing wastewater by coagulation is efficient and coagulation can be an effective pretreatment for roe processing wastewater.The results of this paper for coagulation pretreatment of roe processing wastewater will provide reference for the application in practical production. |
